The Hybrid III Load Sensing Face developed to detect the facial bone fracture type of injury was used in matching tests to establisha protection criterion level corresponding to human fractures. Comparative biomechanical data by Welbourne and others was used as a basis. The Impactor PMTO (post mortem test object) tests in that study were repeated with the Load Sensing Face (LSF) under identical conditions, for example, with the same impactor aiming at corresponding areas on the LSF. The LSF was impacted with a steel bar at various impact speeds. Impacts were aimed at the subnasal maxilla and the nasal bone area. For the nasal area, the Welbourne PMTO data implied a plausible cumulative probability curve of fracture based on impactor energy. The energy corresponding to a 50% risk for nasal fracture was found to be 53 J, (an impactor velocity of 2.53 m/s). The LSF sensors located at the human nasal area measured peak pressure values well above those of other LSF sensors. The average of the LSF peak readings for these sensors showed proportionality with the squared impact velocity, and hence the energy. By entering the pressure (p) versus the impactor velocity (v) graph at the appropriate velocity, a pressure level for a particular velocity can be determined. These results indicate that the LSF detects a 50% risk of sustaining a nasal fracture if the peak pressure measured by the nasal sensors G or H exceeds 2.5 MPa.
Samenvatting